Use the GitHub API to check whether a given user is sponsoring you.

isUserSponsoringMe.ts

/**
 * A function that will return whether the given user is sponsoring you.
 * Requires a personal access token from GitHub.
 * See https://docs.github.com/en/github/authenticating-to-github/keeping-your-account-and-data-secure/creating-a-personal-access-token
 *
 * @param userA The sponsoring user.
 */
async function isUserSponsoringMe(username: string) {
  const res = await fetch('https://api.github.com/graphql', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `bearer ${process.env.YOUR_GITHUB_PERSONAL_ACCESS_TOKEN}`,
    },
    body: JSON.stringify({
      query: `
        query { 
          user(login: "${process.env.YOUR_GITHUB_ID}") { 
            isSponsoredBy(accountLogin: "${username}") 
          } 
        }
      `,
    }),
  }).then((res) => res.json())

  return res?.data?.user?.isSponsoredBy || false
}